Increased Glenohumeral Joint Loads Due to a Supraspinatus Tear Can Be Reversed With Rotator Cuff Repair: A Biomechanical Investigation

Arthroscopic rotator cuff repair in active patients younger than 45 Years: a prospective analysis with a mean 5-year follow-up

Background

To report clinical and activity-specific outcomes after arthroscopic rotator cuff repair (ARCR) for full-thickness supraspinatus tears in active individuals aged less than or equal to 45 years. The pre hoc hypothesis was that patients in this age group would demonstrate significant improvements in clinical outcomes following ARCR along with a significant improvement of athletic abilities.

Methods

Patients were included in this study if they were (1) active individuals aged between 18 and 45 years at the time of surgery, (2) had a full-thickness rotator cuff tear of the supraspinatus tendon with or without anterior or posterior extension, and (3) underwent ARCR. Preoperative and postoperative patient-reported outcomes scores including the American Shoulder and Elbow Surgeons (ASES) score; Disabilities of Arm, Shoulder and Hand; Single Assessment Numeric Evaluation; and Short Form-12 Physical Component Summary were prospectively collected and postoperative patient satisfaction (scale of 1-10) was recorded at a minimum of 2 years postoperatively. Attainment of the minimal clinically important difference and patient acceptable symptom state for the ASES was calculated. Athletic activity-specific outcomes and return to activity were investigated prospectively via a custom-made comprehensive questionnaire.

Results

Between November 2005 and June 2020, of 1149 RCRs performed by the senior author, 54 patients (mean age 40.9 years, 13 female; follow-up 69.7 ± 35.2 months in a range of 24.6-179.6 months) were included into the outcomes analysis. Of those, 4 patients (7.4%) had progressed to revision RCR. At a follow-up of 5.8 years, outcome scores had significantly improved compared to preoperative baselines (ASES 55.6 ± 13.8 to 90.1 + 15.8; P < .001; Disabilities of Arm, Shoulder and Hand 38.9 ± 18.4 to 11.9 ± 17.1; P < .001, Single Assessment Numeric Evaluation 60.7 ± 22.7 to 79.3 ± 27.6; P = .001, Short Form-12 Physical Component Summary 41.6 ± 8.3 to 51.9 ± 9.0; P ≤ .001). Ninety three point six percent of the patients reached the minimal clinically important difference and 72.6% reached the patient acceptable symptom state. Median satisfaction was 9.5/10. Eighty six percent of the patients returned to sports, while 67% of the patients returned to a similar level compared to preoperatively. All sport-specific metrics such as shoulder strength and endurance (P < .001), intensity (P < .001), and impairments from pain affecting speed (P = .002), endurance (P = .002), and competition (P < .001) significantly improved postoperatively.

Conclusion

ARCR of full-thickness rotator cuff tear in active individuals aged 45 years or less results in a clinically relevant improvement of outcomes, function, and quality of life at a minimum of 2 years and mean 5.8-year follow-up with a low rate of revision. While 86% of patients were able to return to activity and sport-specific outcome metrics significantly and substantially improved compared to preoperatively, a return to preinjury levels was not reliably achieved in all patients, with particular limitations observed in overhead active individuals. The data support the hypothesis that patients in this age group demonstrate significant improvements in clinical outcomes following ARCR along with significant improvements in athletic abilities.

Tuberoplasty reduces resistance force in dynamic shoulder abduction for irreparable rotator cuff tears: a cadaveric biomechanical study

BACKGROUND

Arthroscopic tuberoplasty is an optional technique for managing irreparable rotator cuff tears. However, there is a lack of studies investigating the resistance force during shoulder abduction in cases of irreparable rotator cuff tears and tuberoplasty.

HYPOTHESES

In shoulders with irreparable rotator cuff tears, impingement between the greater tuberosity (GT) and acromion increases the resistance force during dynamic shoulder abduction. Tuberoplasty is hypothesized to reduce this resistance force by mitigating impingement.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight cadaveric shoulders, with a mean age of 67.75 years (range, 63-72 years), were utilized. The testing sequence included intact rotator cuff condition, irreparable rotator cuff tears (IRCTs), burnishing tuberoplasty, and prosthesis tuberoplasty. Burnishing tuberoplasty refers to the process wherein osteophytes on the GT are removed using a bur, and the GT is subsequently trimmed to create a rounded surface that maintains continuity with the humeral head. Deltoid forces and actuator distances were recorded. The relationship between deltoid forces and actuator distance was graphically represented in an ascending curve. Data were collected at five points within each motion cycle, corresponding to actuator distances of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm.

RESULTS

In the intact rotator cuff condition, resistance forces at the five points were 34.25 ± 7.73 N, 53.75 ± 7.44 N, 82.50 ± 14.88 N, 136.25 ± 30.21 N, and 203.75 ± 30.68 N. In the IRCT testing cycle, resistance forces were 46.13 ± 7.72 N, 63.75 ± 10.61 N, 101.25 ± 9.91 N, 152.5 ± 21.21 N, and 231.25 ± 40.16 N. Burnishing tuberoplasty resulted in resistance forces of 32.25 ± 3.54 N, 51.25 ± 3.54 N, 75.00 ± 10.69 N, 115.00 ± 10.69 N, and 183.75 ± 25.04 N. Prosthesis tuberoplasty showed resistance forces of 29.88 ± 1.55 N, 49.88 ± 1.36 N, 73.75 ± 7.44 N, 112.50 ± 7.07 N, and 182.50 ± 19.09 N. Both forms of tuberoplasty significantly reduced resistance force compared to IRCTs. Prosthesis tuberoplasty further decreased resistance force due to a smooth surface, although the difference was not significant compared to burnishing tuberoplasty.

CONCLUSION

Tuberoplasty effectively reduces resistance force during dynamic shoulder abduction in irreparable rotator cuff tears. Prosthesis tuberoplasty does not offer a significant advantage over burnishing tuberoplasty in reducing resistance force.

CLINICAL RELEVANCE

Tuberoplasty has the potential to decrease impingement, subsequently reducing resistance force during dynamic shoulder abduction, which may be beneficial in addressing conditions like pseudoparalysis.

Lower Trapezius Transfer Improves Clinical Outcomes With a Rate of Complications and Reoperations Comparable to Other Surgical Alternatives in Patients with Functionally Irreparable Rotator Cuff Tears: A Systematic Review

PURPOSE

To analyze the clinical outcomes of lower trapezius transfer (LTT) for patients with functionally irreparable rotator cuff tears (FIRCT) and summarize the available literature regarding complications and reoperations.

METHODS

After registration in the International prospective register of systematic reviews (PROSPERO [CRD42022359277]), a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. Inclusion criteria were English, full-length, peer-reviewed publications with a level of evidence IV or higher reporting on clinical outcomes of LTT for FIRCT. Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus via Elsevier databases were searched. Clinical data, complications and revisions were systematically recorded.

RESULTS

Seven studies with 159 patients were identified. The mean age range was 52 to 63 years, 70.4% of the patients included were male, and the mean follow-up time ranged between 14 and 47 months. At final follow-up, LTT lead to improvements in range of motion, with reported forward elevation (FE) and external rotation (ER) mean gains of 10° to 66° and 11° to 63°, respectively. ER lag was present before surgery in 78 patients and was reversed after LTT in all shoulders. Patient-reported outcomes were improved at final follow-up, including the American Shoulder and Elbow Society score, Shoulder Subjective Value and Visual Analogue Scale. The overall complication rate was 17.6%, and the most reported complication was posterior harvest site seroma/hematoma (6.3%). The most common reoperation was conversion to reverse shoulder arthroplasty (5%) with an overall reoperation rate of 7.5%.

CONCLUSIONS

Lower trapezius transfer improves clinical outcomes in patients with irreparable rotator cuff tears with a rate of complications and reoperations comparable to other surgical alternatives in this group of patients. Increases in forward flexion and ER are to be expected, as well as a reversal of ER lag sign when present before surgery.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III-IV studies.

Anterior Latissimus Dorsi Transfer for Irreparable Subscapularis Tears Improves Shoulder Kinematics in a Dynamic Biomechanical Cadaveric Shoulder Model

BACKGROUND

In young patients with irreparable subscapularis deficiency (SSC-D) and absence of severe osteoarthritis, anterior latissimus dorsi transfer (aLDT) has been proposed as a treatment option to restore the anteroposterior muscular force couple to regain sufficient shoulder function. However, evidence regarding the biomechanical effect of an aLDT on glenohumeral kinematics remains sparse.

PURPOSE/HYPOTHESIS

The purpose of this study was to investigate the effects of an aLDT on range of glenohumeral abduction motion, superior migration of the humeral head (SM), and cumulative deltoid force (cDF) in a simulated SSC-D model using a dynamic shoulder model. It was hypothesized that an aLDT would restore native shoulder kinematics by reestablishing the insufficient anteroposterior force couple.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric shoulders were tested using a validated shoulder simulator. Glenohumeral abduction angle (gAA), SM, and cDF were compared across 3 conditions: (1) native, (2) SSC-D, and (3) aLDT. gAA and SM were measured using 3-dimensional motion tracking, while cDF was recorded in real time during dynamic abduction motion by load cells connected to actuators.

RESULTS

The SSC-D significantly decreased gAA (Δ-9.8°; 95% CI, -14.1° to -5.5°; P < .001) and showed a significant increase in SM (Δ2.0 mm; 95% CI, 0.9 to 3.1 mm; P = .003), while cDF was similar (Δ7.8 N; 95% CI, -9.2 to 24.7 N; P = .586) when compared with the native state. Performing an aLDT resulted in a significantly increased gAA (Δ3.8°; 95% CI, 1.8° to 5.7°; P < .001), while cDF (Δ-36.1 N; 95% CI, -48.7 to -23.7 N; P < .001) was significantly reduced compared with the SSC-D. For the aLDT, no anterior subluxation was observed. However, the aLDT was not able to restore native gAA (Δ-6.1°; 95% CI, -8.9° to -3.2°; P < .001).

CONCLUSION

In this cadaveric study, performing an aLDT for an irreparable subscapularis insufficiency restored the anteroposterior force couple and prevented superior and anterior humeral head migration, thus improving glenohumeral kinematics. Furthermore, compensatory deltoid forces were reduced by performing an aLDT.

CLINICAL RELEVANCE

Given the favorable effect of the aLDT on shoulder kinematics in this dynamic shoulder model, performing an aLDT may be considered as a treatment option in patients with irreparable SSC-D.

Compensation strategy of shoulder synergist muscles is not stereotypical in patients with rotator cuff repair

Rotator cuff tear is a common shoulder injury that causes shoulder dysfunction and pain. Although surgical repair is the primary treatment for rotator cuff tear, it is well recognized that impaired force exertion of muscles connecting to the involved tendon and subsequent complemental change in the force exertion of synergist muscles persist even after repair. This study aimed to identify the compensation strategy of shoulder abductors by examining how synergist muscles respond to supraspinatus (SSP) muscle force deficit in patients with rotator cuff repair. Muscle shear modulus, an index of muscle force, was assessed for SSP, infraspinatus, upper trapezius, and middle deltoid muscles in repaired and contralateral control shoulders of 15 patients with unilateral tendon repair of the SSP muscle using ultrasound shear wave elastography while the patients passively or actively held their arm in shoulder abduction. In the repaired shoulder, the shear modulus of the SSP muscle declined, whereas that of other synergist muscles did not differ relative to that of the control. To find the association between the affected SSP and each of the synergist muscles, a regression analysis was used to assess the shear moduli at the population level. However, no association was observed between them. At the individual level, there was a tendency of variation among patients with regard to a specific muscle whose shear modulus complementarily increased. These results suggest that the compensation strategy for SSP muscle force deficit varies among individuals, being nonstereotypical in patients with rotator cuff injury.

Contact Mechanics of Elliptical and Spherical Head Implants during Axial Rotation in Anatomic Total Shoulder Arthroplasty: A Biomechanical Comparison

BACKGROUND

Elliptical humeral head implants have been proposed to result in more anatomic kinematics following total shoulder arthroplasty (aTSA). The purpose of this study was to compare glenohumeral contact mechanics during axial rotation using spherical and elliptical humeral head implants in the setting of aTSA.

METHODS

Seven fresh-frozen cadaveric shoulders were utilized for biomechanical testing in neutral (NR), internal (IR), and external (ER) rotation at various levels of abduction (0°, 15°, 30°, 45°, 60°) with lines of pull along each of the rotator cuff muscles. Each specimen underwent the following three conditions: (1) native, and TSA using (2) an elliptical and (3) spherical humeral head implant. Glenohumeral contact mechanics, including contact pressure (CP; kPa), peak contact pressure (PCP; kPa), and contact area (CA; mm2), were measured in neutral rotation as well as external and internal rotation using a pressure mapping sensor.

RESULTS

Elliptical head implants showed a significantly lower PCP in ER compared to spherical implants at 0° (Δ-712.0 kPa; p = 0.034), 15° (Δ-894.9 kPa; p = 0.004), 30° (Δ-897.7 kPa; p = 0.004), and 45° (Δ-796.9 kPa; p = 0.010) of abduction, while no significant difference was observed in ER at 60° of abduction or at all angles in NR and IR. Both implant designs had similar CA in NR, ER, and IR at all tested angles of abduction (p > 0.05, respectively).

CONCLUSIONS

In the setting of aTSA, elliptical heads showed significantly lower PCP during ER at 0° to 45° of abduction, when compared to spherical head implants. However, in NR and IR, PCP was similar between implant designs. Both designs showed similar CA during NR, ER, and IR at all abduction angles.

LEVEL OF EVIDENCE

basic science; controlled laboratory study.

Physiological Tensioning During Lower Trapezius Transfer for Irreparable Posterosuperior Rotator Cuff Tears May Be Important for Improvement in Shoulder Kinematics

BACKGROUND

Lower trapezius transfer (LTT) has been proposed for restoring the anteroposterior muscular force couple in the setting of an irreparable posterosuperior rotator cuff tear (PSRCT). Adequate graft tensioning during surgery may be a factor critical for sufficient restoration of shoulder kinematics and functional improvement.

PURPOSE/HYPOTHESIS

The purpose was to evaluate the effect of tensioning during LTT on glenohumeral kinematics using a dynamic shoulder model. It was hypothesized that LTT, while maintaining physiological tension on the lower trapezius muscle, would improve glenohumeral kinematics more effectively than undertensioned or overtensioned LTT.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 10 fresh-frozen cadaveric shoulders were tested using a validated shoulder simulator. Glenohumeral abduction angle, superior migration of the humeral head, and cumulative deltoid force were compared across 5 conditions: (1) native, (2) irreparable PSRCT, (3) LTT with a 12-N load (undertensioned), (4) LTT with a 24-N load (physiologically tensioned according to the cross-sectional area ratio of the lower trapezius muscle), and (5) LTT with a 36-N load (overtensioned). Glenohumeral abduction angle and superior migration of the humeral head were measured using 3-dimensional motion tracking. Cumulative deltoid force was recorded in real time throughout dynamic abduction motion by load cells connected to actuators.

RESULTS

Physiologically tensioned (Δ13.1°), undertensioned (Δ7.3°), and overtensioned (Δ9.9°) LTT each significantly increased the glenohumeral abduction angle compared with the irreparable PSRCT (P < .001 for all). Physiologically tensioned LTT achieved a significantly greater glenohumeral abduction angle than undertensioned LTT (Δ5.9°; P < .001) or overtensioned LTT (Δ3.2°; P = .038). Superior migration of the humeral head was significantly decreased with LTT compared with the PSRCT, regardless of tensioning. Physiologically tensioned LTT resulted in significantly less superior migration of the humeral head compared with undertensioned LTT (Δ5.3 mm; P = .004). A significant decrease in cumulative deltoid force was only observed with physiologically tensioned LTT compared with the PSRCT (Δ-19.2 N; P = .044). However, compared with the native state, LTT did not completely restore glenohumeral kinematics, regardless of tensioning.

CONCLUSION

LTT was most effective in improving glenohumeral kinematics after an irreparable PSRCT when maintaining physiological tension on the lower trapezius muscle at time zero. However, LTT did not completely restore native glenohumeral kinematics, regardless of tensioning.

CLINICAL RELEVANCE

Tensioning during LTT for an irreparable PSRCT may be important to sufficiently improve glenohumeral kinematics and may be an intraoperatively modifiable key variable to ensure postoperative functional success.

Superior Capsular Reconstruction Partially Restores Native Glenohumeral Joint Loads In A Dynamic Biomechanical Shoulder Model

PURPOSE

To evaluate the effect of an irreparable posterosuperior rotator cuff tear (PSRCT) on glenohumeral joint loads and to quantify improvement following superior capsular reconstruction (SCR) using an acellular dermal allograft.

METHODS

Ten fresh-frozen cadaveric shoulders were tested using a validated dynamic shoulder simulator. A pressure mapping sensor was placed between the humeral head and glenoid surface. Each specimen underwent the following conditions: (1) native, (2) irreparable PSRCT, (3) SCR using a 3mm-thick acellular dermal allograft. Glenohumeral abduction angle (gAA) and superior humeral head migration (SM) were measured using 3D motion tracking software. Cumulative deltoid force (cDF) and glenohumeral contact mechanics, including contact area (gCA) and contact pressure (gCP), were assessed at rest,15°,30°,45°, and maximum angle of glenohumeral abduction.

RESULTS

The PSRCT resulted in a significant decrease of gAA along with an increase in SM, cDF, and gCP (P<.001, respectively). SCR did not restore native gAA (P<.001), however, SM was significantly reduced (P<.001). Further, SCR significantly reduced deltoid forces at 30° (P=.007) and 45° of abduction (P=.007) when compared to the PSRCT. SCR did not restore native cDF at 30°(P=.015), 45°(P<.001), and maximum angle (P<.001) of glenohumeral abduction. Compared to the PSRCT, SCR resulted in a significant decrease of gCP at 15°(P=.008), 30°(P=.002), and 45°(P=.006). However, SCR did not completely restore native gCP at 45° (P=.038) and maximum abduction angle (P=.014).

CONCLUSION

In this dynamic shoulder model, SCR only partially restored native glenohumeral joint loads. However, SCR significantly decreased glenohumeral contact pressure, cumulative deltoid forces, and superior migration, while increasing abduction motion, when compared to the posterosuperior rotator cuff tear.

CLINICAL RELEVANCE

These observations raise concerns regarding the true joint preserving potential of SCR for an irreparable posterosuperior rotator cuff tear, along with its ability to delay progression of cuff tear arthropathy and eventual conversion to reverse shoulder arthroplasty.

Management of Irreparable Posterosuperior Rotator Cuff Tears-A Current Concepts Review and Proposed Treatment Algorithm by the AGA Shoulder Committee

Posterosuperior rotator cuff tears range among the most common causes of shoulder complaints. While non-operative treatment is typically reserved for the elderly patient with low functional demands, surgical treatment is considered the gold standard for active patients. More precisely, an anatomic rotator cuff repair (RCR) is considered the most desirable treatment option and should be generally attempted during surgery. If an anatomic RCR is impossible, the adequate choice of treatment for irreparable rotator cuff tears remains a matter of debate among shoulder surgeons. Following a critical review of the contemporary literature, the authors suggest the following evidence- and experience-based treatment recommendation. In the non-functional, osteoarthritic shoulder, treatment strategies in the management of irreparable posterosuperior RCT include debridement-based procedures and reverse total shoulder arthroplasty as the treatment of choice. Joint-preserving procedures aimed at restoring glenohumeral biomechanics and function should be reserved for the non-osteoarthritic shoulder. Prior to these procedures, however, patients should be counseled about deteriorating results over time. Recent innovations such as the superior capsule reconstruction and the implantation of a subacromial spacer show promising short-term results, yet future studies with long-term follow-up are required to derive stronger recommendations.

Technical Guide and Tips to Posterior Arthroscopic Latissimus Dorsi Transfer for Irreparable Posterosuperior Rotator Cuff Tears

Latissimus dorsi (LD) transfer is a reliable treatment option for irreparable posterosuperior (PS) rotator cuff tears in young and active patients that need to recover the range of motion for their daily living activities. The technique starts with an arthroscopic assessment of the tear. The next step is the mini-open stage for muscle release from the subcutaneous layer of the skin, the teres major (TM), the triceps, and the lateral border and inferior angle of the scapula. Later, the scope is used to prepare the footprint (arthroscopy) and for the release and the harvest of the tendon (endoscopy), taking care not to detach the TM and not to damage the radial nerve. A grasper is used to push the LD to its correct path medial to the triceps. After that the same instrument is placed from the anterolateral and the anterior arthroscopic portals toward the mini-open incision to catch the sutures previously loaded on the LD tendon with Krackow stitches. The LD is transferred to the greater tuberosity and is attached with one medial and one lateral knotless anchors. A third point of fixation enables a partial RC repair and ensures a surface of bone to tendon healing.